As is well known, there is a difference of several hundred percent between the cost of commercial electricity during peak and off-peak hours. Several systems have already been designed to take advantage of this fact, perhaps the best known being one in which water is pumped up-hill to a storage facility (such as a mountain lake) during off-peak hours and then allowed to flow down-hill through a turbine during peak hours. Although this system is obviously tremendously inefficient in one sense, the cost of the electricity used to store the energy during off-peak hours (that is, to pump the water up-hill) is so much less than the selling price of the electricity during peak hours (when the stored energy is used to turn the turbine) that the system is commercially feasible.
Another prior-art method for generating electricity which is relevant to the presently preferred embodiment of the invention takes advantage of the difference in density between surface water and very deep water, the difference in density being due to their difference in temperature and pressure. Thus, systems have been designed in which dense cold water from far beneath the surface of a body of water is channeled upwardly through a vertical pipe of large diameter at the top of which a turbine wheel is turned by the rising water.
Another prior-art technique may be relevant to the presently preferred embodiment of the invention although it is not a method of generating electricity. Compressed air forced to an end of a pipe immersed beneath water and used to push water up the pipe has been used in connection with dredging operations and in connection with the recovery of doubloons along the Florida coasts. Although of no relevance to dredging or doubloon recovery operations, I have observed that, the deeper the submerged end of the pipe, the greater the velocity of the water exiting the top of the pipe.
Another prior art device consists of turbines or pistons in cylinder mechanisms or small comparable devices called "air motors." Such devices operate by using compressed air to cause a crank shaft to rotate, thereby providing the rotating power to operate winches where the use of other power causes hazards.